1. Field of the Invention
The disclosures herein generally relate to a coordinate detector and an electronic information board system.
2. Description of the Related Art
Recently, electronic information boards, so-called electronic whiteboards or interactive white boards (IWB), have progressively been developed. This type of the electronic information board may, for example, generally include an image display device having a large screen composed of a flat panel such as a liquid crystal panel or a plasma panel (e.g., a screen having a dimension range in a diagonal direction of 40 to 60 inch), a touch panel (a coordinate detector) configured to detect coordinates of a position touched on a display surface of the image display device, and a control device configured to display various types of images (images including characters, numbers, and graphics) written on the display surface of the image display device based on coordinate data output from the coordinate detector.
Further, the electronic information board may be connected to a personal computer (PC). Such electronic information board connected to the PC may be able to enlarge an image displayed on the PC to display the enlarged image on the electronic board, which may be used for the presentation in a conference.
In addition, an electronic information board system includes a function to superpose hand-written graphics written by a pen-shaped input device on the image of the display surface by allowing the pen-shaped input device (a detection target) to touch the touch panel, or a function to incorporate an image of the PC to superpose hand-written graphics written by the pen-shaped input device on the image incorporated from the PC.
Further, an example of the coordinate detector disposed in the electronic information board system may be configured to include a pair of light sensor units disposed at opposite end corners of one side of a frame enclosing four sides of a display part, and three optical reflective members disposed on respective side walls perpendicular to the display surface of the remaining three sides of the frame. In the coordinate detector, light (infrared radiation) emitted from the pair of the light sensor units is applied to two optical reflective members facing each other at a predetermined angle out of the three optical reflective members disposed on the remaining three sides of the frame. Respective attached positions and attached angles of the two light sensor units are determined such that the pair of the two light sensor units receives light reflected off each of the two optical reflective members. In this configuration, when the pen-shaped input device touches the display surface, light passing through the touched position is blocked off and not received by the light sensor units. At this moment, the coordinate positions are computed by the triangulation method based on the optical angles.